ddr: imx9: enable Performance monitor counter

Add Kconfig for enabling reference events counter in DDRC performance
monitor by default

Signed-off-by: Ye Li <ye.li@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/drivers/ddr/imx/imx9/Kconfig b/drivers/ddr/imx/imx9/Kconfig
index a16ddc6..123ad17 100644
--- a/drivers/ddr/imx/imx9/Kconfig
+++ b/drivers/ddr/imx/imx9/Kconfig
@@ -11,6 +11,12 @@
 	help
 	  Select the i.MX9 LPDDR4/4X driver support on i.MX9 SOC.
 
+config IMX9_DRAM_PM_COUNTER
+	bool "imx9 DDRC performance monitor counter"
+	default y
+	help
+	  Enable DDR controller performance monitor counter for reference events.
+
 config SAVED_DRAM_TIMING_BASE
 	hex "Define the base address for saved dram timing"
 	help